I was planning on changing out my differential oil in the near future. It's only been 3 1/2 years . So I bought some Red Line 75W90NS (raceshopper.com). At least that's what I ordered (packing list confirmed it). They ended up sending regular 75W90. I decided on the NS based on searches here. I found out some used one, others used the other when it came to Red Line. My car is a daily driver. I do like to drive it hard once in a while. I do like to track it once in a while too, but it has been that same 3 1/2 years. So it doesn't happen much. So my question is, should I bother returning it (at their cost of course) to get the NS? Or should I just say screw it and go with the regular stuff? Does it just not mater that much? Please, no recs to go with Royal Purple or Amsoil or NEO or whatever. I know they are good too. I went with RL. I read here to also not go with MT-90 or MTL for the diffy.

TIA

Jeff

 

Copy and pasted from Redline's site:

75W90NS - recommended for manual transmissions and non-limited-slip transaxles that recommend 90 WT oils. Can be used in racing limited-slip units to increase lockup and reduce wheel spin. Street-driven rear-wheel drive cars should use regular Red Line 75W90 or 80W140.

75W90 is just fine; I've been using it without issue for years.

 

75W90 GEAR OIL - recommended for most street driven and racing differentials. Excellent performance in conventional and limited-slip units. Also for limited-slip manual transaxles which require a 90 WT oil. Contains limited-slip friction modifiers.

75W90NS - recommended for manual transmissions and non-limited-slip transaxles that recommend 90 WT oils. Can be used in racing limited-slip units to increase lockup and reduce wheel spin. Street-driven rear-wheel drive cars should use regular Red Line 75W90 or 80W140.


I went with the 75W90, as our cars have an LSD, and this is what Redline themselves reccomend.

 

Our limited slip is a Torsen which does not have CLUTCH TYPE PLATES and thus does not need the friction modifers that are not in this oil.

 

cewrx7r1... that is my understanding and why I thought the NS stuff was more appropriate. I read the Red Line web site info. I knew our differential was an LSD, but without the clutches. The clutch type would need the friction modifiers. Thus my confusion. And so it seems it doesn't matter that much. Thanks for all input guys.

 

Here's a response I got from Red Line regarding my original question (probably shoulda started with them LOL).

 

Hello-

The only benefit to having zero friction modifiers (i.e. the NS fluids) is that syncros may be happier. For really testy transmissions, like pre-1987 Porsches, it is an absolute necessity. For the RX-7, it's nice, but it won't kill you.

For the diff, whether it be torsen, clutch-type, or open, some friction modifiers are a nice thing to have.

Take care,
Shad

 

Personally I wasn't happy with Red Line in my trans. It was notchy when cold. I replaced it with Royal Purple, which I like much better. I think a lot of people go with Red Line because of the name...

 

I'm putting Red Line in my diffy. I already have RP in my tranny. Right now, shifting isn't that smooth.

 

If it's been in there for 3.5 years, that would explain it.

I'm also running Royal Purple and like it a lot.

 

Ha ha... nope, the RP was put in last fall. It's the diffy fluid that's been in there 3.5 years! It is so due. However, that one plastic piece (maybe a bushing?) that prevents the shifter from rotating is broken. I just keep forgetting to get a new one.

 

I do have Red Line in my diff. It seems to be working just fine.

cvs

 

Can't you just buy the NS additive seperately, and add to the fill up?

 

NS is the one without the additive, and where you'd want to start to see if there's a difference between the NS and the non-NS. I would think there are friction modifiers you can add separately. But I don't know for sure. I'm sticking withe the non-NS (with the friction modifiers) based on what Dave at RL said (see above).

 

Whats wrong with the Redline MT-90?

 

the torsen works based largely on friction, as does disc type lsd's. both will turn the oil black after several driver ed days, due to extreme frictional heat.

the torsen can be tuned for more or less lock, with oil selection. I found RL 75w90, that has some lsd modifier (slick stuff), was still to grabby for wet weather use. I use the extra shot of RL modifier, for less lock. the RL xxxNS would be too much lock for me, but good for drag strip.

 

I recently filled my tranny with Redline MT-90 and experienced notchiness that didn't exist before. It's particularly noticable when the engine is cold.

I've had no such problems in the past with Castrol Syntec and Mobil 1 gear oil. Based on my experience I'd stick with a synthetic gear oil for my tranny that contains modifiers, which are apparently absent in Redline MT-90 and MTL.

 

It's all about RP................ my car didn't like RL...........

 

I already have the redline MT-90....if i dont like it can i add a modifier later? First RWD car still learning about it.

 

CRC, K&W, and Sta-Lube all sell a gear oil additive that contains modifiers. You should be able to find it at Pep Boys or Discount Auto Parts for between $4 & $5.

The exact name of the product is Trans-X Posi-Trac Limited Slip Gear Oil Additive (also for use in transmissions). If you haven't already put the Redline MT-90 in your tranny, if at all possible, I'd return it to the store for a refund. Use the Redline 75w90 gear oil or the Castrol Syntec or Royal Purple. Otherwise you can try the additive and see how it works. That's precisely what I intend to do this weekend.

 

damn, all this damn oil talk is crazy

so according to the info listed on this thread

diff (is this the same as gear oil) - we should go with redline 75w90

transmission - we should also go with redline 75w90?

people who have used RL 75w90 please respond with your exp.. thanks guys

 

^Redline MT-90 for the transmission and 75W90 for the diff.

 

word............

 

It doesn't matter which synthetic gear oil you use in your transmission (IMHO), Castrol Syntec, Mobil 1, Redline, etc., as long as it is a 75w90 with the friction modifiers and NOT, I repeat NOT, Redline MTL or MT-90.

Redline MTL and MT-90 has no or almost no friction modifiers, thus the problem with notchiness that some of us have experienced. A friend of mine who had experience with the Redline MTL warned me not to use it in my transmission. I had already bought the Redline MT-90 for my transmission so I put it in. And I am sorry that I did. I may try to add the friction modifier I alluded to in my earlier post or just dump the Redline MT-90 in favor of a gear oil that already has the friction modifiers in it. I also plan to contact Redline as soon as I can regarding this issue. I've heard of way too many people having issues their MTL and MT-90.

 

I wonder if he ever got a-hold of Redline?
Anyone else believe MTL or MT-90 should not be used in the transmission?